Personality Disorder Assessment in the Differential Diagnosis of Autism Spectrum Disorders in Adults

Background: Given the common features of rigidity of thinking, persistence and pervasiveness of symptoms, and the negative impact on one's functioning, the differential diagnosis between an Autism Spectrum Disorder (ASD) and a Personality Disorder (PD) in adults can be difficult. Many of the characteristic features of ASD resemble traits associated with specific personality disorders, particularly the odd or eccentric Cluster A PD’s, and inadequate characterization of personality and neurodevelopmental disorders in adults referred for a diagnostic evaluation could lead to misdiagnosis. However, the use of PD instruments in the assessment of adults with ASD’s is relatively uncommon and vice versa. Personality assessment in combination with the Autism Diagnostic observation Schedule (ADOS) can provide a more comprehensive characterization of the interpersonal and emotional difficulties experienced by these adults and improve specificity of diagnosis. 
Objectives: We present the case of MR, a 42-year old male who was referred by his treating psychiatrist for evaluation of possible ASD, such as Asperger’s Disorder. MR has a history of depression, persistent social isolation, and pervasive anxiety as well as academic and employment difficulties. Previous diagnoses have included Schizoaffective Disorder, Major Depressive Disorder, Paranoid Schizophrenia, and anxiety. Additionally, symptoms of grandiosity and odd thinking were observed.
Methods: MR was administered a comprehensive battery of neuropsychological and behavioral instruments that included measures of intelligence, academic achievement, visuospatial processing, and fine motor functioning as well as a questionnaire specific to symptoms of inattention. In addition, MR was administered Module 4 of the ADOS, the Structured Interview for DSM-IV Personality (SID-P), and a self-report measure of personality.
Results: MR met criteria for Autistic Disorder based upon the ADOS. In addition, he met criteria for Narcissistic PD and was one symptom below criteria for five other PD’s. MR also demonstrated bilateral fine motor deficits. Otherwise, his neurocognitive abilities were well-developed.
Conclusions: MR’s symptom profile and test performance were most consistent with Autistic Disorder. However, conclusions were limited based upon his refusal to allow the examiner to contact family members in order to confirm age of symptom onset, and the diagnosis of Autism was made provisionally pending substantiation of developmental history. Although MR exhibited characteristics of several personality disorders, particularly Narcissistic Personality Disorder, these traits existed within the context of Autism rather than a PD. Specifically, his symptoms were primarily related to a lack of insight regarding social relationships rather than a wanton disregard for the feelings of others.